Abstract
For pt.II see ibid., vol.14, p.653 (1984). The trend in the lattice parameters of the actinide nitride series is interpreted in terms of metallic 5f-5f and covalent cation 5f-anion 2p contributions to the calculated equations of state. The lattice parameters are obtained from self-consistent LMTO, RLMTO and spin-polarised LMTO calculations. Particularly large magnetovolume effects were found for NpN-AmN. Spin-orbit splitting also increased the calculated volumes of NpN-AmN and the density of states at the Fermi level was found to be predominantly of 5f5/2 character for the paramagnetic ground states of UN-AmN.